Bump docker/build-push-action from 2 to 6

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 2 to 6.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v2...v6)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/continuous-deployment.yml

@@ -55,7 +55,7 @@ jobs:
         run: echo "image_name=${{ secrets.GCP_DOCKER_REGISTRY }}/${{ secrets.GCP_PROJECT_ID }}/${{ secrets.GCP_DOCKER_REPOSITORY }}/${{ matrix.app }}" >> $GITHUB_ENV
 
       - name: Build and push
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: ./docker/deploy/${{ matrix.app }}/Dockerfile